الفهرس 
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Abstract
This study investigated the effect of whole body low-dose radiation (10 cGy of 6 MeV x-rays) given prior to a challenging dose of 2Gy x-rays on adaptive response of the liver of rats. Materials and Methods: Rats were either irradiated with 10 cGy, 2Gy or 10 cGy 24h prior to 2Gy (10 cGy-2Gy irradiated). Liver samples were analysed for apoptosis, caspase-3, Bcl-2, by flow cytometery. DNA damage was determined by alkaline comet assay. The protein damage, lipid damage, and expression of endogenous antioxidants, Il-1β, Il-6, and TNF-α were determined by ELISA. Results: An increase in apoptosis paralleled with increase in DNA damage and expression of Il-1β, Il-6, and TNF-α, protein oxidation and lipid peroxidation were detected in all irradiated groups. The irradiated rats with 10 cGy-2Gy and the 2Gy-irradiated showed the highest effect. The increase in oxidative damage of protein and lipid was accompanied with depletion of endogenous antioxidants. In all cases, the10 cGy-2Gy irradiated group showed similar or higher effect than the 2Gy-irradiated group. In conclusions, under the present experimental conditions, there is no evidence that 10 cGy-irradiation protected the liver cells against a subsequent higher dose. The significant effect of 10 cGy-irradiation emphasizes the low-dose radiation associated risk.